Bone marrow-derived factors support growth of N-type, but not of melanocytic neuroblastoma cells.

Background: Neuroblastoma and melanoma cells have a common embryonal origin. In contrast to melanoma, most neuroblastoma tumours preferentially metastasize into bone marrow. Previously, we described that bone marrow-conditioned medium (BM-CM) supports the proliferation of catecholamine-producing (N-type) neuroblastoma (SK-N-SH, IMR-32, Kelly)-, but not of melanoma cells. Both neuroblastoma and melanoma produce DOPA (3,4 dihydroxyphenylalanine); while melanoma cells use tyrosinase for DOPA synthesis, neuroblastoma cells usually utilize tyrosine hydroxylase. Results: Certain neuroblastoma cells (in our study: SK-N-LO, LS, SH-EP) express tyrosinase instead of tyrosine hydroxylase for synthesis of DOPA, and do not synthesize catecholamines, as shown by HPLC and RT-PCR analysis. Strikingly and in contrast to catecholamine-producing N-type cells, the proliferation of these melanocytic neuroblastoma cells is not supported by BM-CM. Conclusion: With respect to proliferation in the presence of BM-CM, melanocytic neuroblastoma cells behave more like melanoma cells and may represent the subfraction of neuroblastoma cells with a minor tendency to metastasize into bone marrow.